Safety in the Lab
Written by Seleen S. Collins, Catherine C. Beaucham, & Mike Miller   

Originally published: Fall 2017 Issue (Volume 15, Number 3)
View the Digital Edition here

According to the Bureau of Justice Statistics, in 2014 there were more than 400 publicly funded criminal justice laboratories in the United States. While more than 14,000 employees at these laboratories use technology to identify and protect the nation from criminals, one wonders whether they need protection from potentially harmful exposures encountered in their occupational environment and processes. In fact, with that question in mind, the FBI recently arranged for the National Institute for Occupational Safety and Health (NIOSH) to evaluate its forensic crime laboratory. The FBI’s intent was to assess processes in its own laboratories so that the findings could serve as an example of the types of precautions other forensic laboratories should consider to keep their employees safe.

Most often, concern for the well-being of employees in the face of a known or suspected health risk at the workplace is the motivation for seeking assistance from the NIOSH Health Hazard Evaluation (HHE) program. NIOSH, which is a part of the Centers for Disease Control and Prevention, conducts research and makes recommendations for preventing work-related injury and illness. As part of its mission, the HHE program investigates possible workplace health hazards under the authority of the Occupational Safety and Health Act of 1970. Employees, employers, or union representatives can contact the HHE program about workplace health concerns. Evaluations are conducted by a comprehensive team of experts that provide recommendations for controlling hazards to prevent illness.

Focus of Evaluation

A NIOSH HHE team visited the FBI Laboratory three times over a 28-month period to evaluate the workplace. Although the team looked into job stress and workload-related concerns and included those in its final report, this article focuses on employees’ potential chemical exposures while conducting forensic tests and analyzing specimens.

Evaluation of Worksite

During the first visit to the forensic lab, which has about 800 employees, the HHE team set out to determine which processes and procedures should be the focus of its evaluations. They observed the employees doing their usual daily activities, taking particular interest in the procedures of the 13 case-working units: trace evidence; chemistry; nuclear and mitochondrial deoxyribonucleic acid (DNA); questioned documents; firearms and toolmarks; explosives; latent print operations; operational projects; federal DNA database; chemical, biological, radiological, and nuclear science; scientific response; forensic imaging; and counterterrorism and forensic science research.

After analyzing exposure risks among all the units, the team sought to identify procedures and exposures that presented the greatest potential health risk to employees; assess employee exposures from these higher-risk procedures; and provide recommendations to reduce employees’ chemical exposures where necessary. Full details of the survey performed by the HHE team to prioritize the procedures and exposures for further evaluation are included in the NIOSH report (NIOSH, 2016). The team observed the 25 procedures of greatest health risk; then, according to their professional judgement, they selected 10 procedures for personal exposure monitoring.

The prioritization strategy helped the HHE team narrow the focus of the assessment to those tasks with higher risk relative to other tasks. The procedures selected for assessment were in these units: nuclear and mitochondrial DNA; firearms and toolmarks; latent print operations; and operational projects. The team sampled the workplace air for ethyl cyanoacrylate, methanol, methylene chloride, and particles; observed the use of formamide; sampled surfaces for lead; and evaluated ventilation in the firing range and at the wet bullet trap. Additional information on the specific monitoring in each unit is provided below. Full details of the sampling and analytical methods are included in the NIOSH report (NIOSH 2016).

Nuclear and Mitochondrial DNA Unit

Employees in this unit examined evidence using serological, mitochondrial DNA, and nuclear DNA methodologies. Specimens included body fluid stains or other biological tissues, as well as hair, bone, or teeth fragments. Potential chemical exposures included phenol, pyridine, chloroform, isoamyl alcohol, and formamide. The HHE team noted that lab employees typically handled chemicals in a three-sided, non-ventilated enclosure (Figure 1), but some tasks using formamide were performed on the open benchtop. Personal protective equipment (PPE) included nitrile gloves, cloth lab coats, and safety glasses with side shields. Surgical masks were worn to protect the evidence from contamination by the wearer.

Because the units worked with only small quantities of formamide (about 20 mL per day), the team determined that typical use of formamide would not likely result in exposures above the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 10 parts per million (ppm). In addition, because of its vapor pressure (0.08 millimeters of mercury at room temperature), formamide is unlikely to evaporate quickly. Therefore, the likeliest employee exposure would be skin exposure from a spill and subsequent cleanup. Employees had a spill cleanup procedure that included wearing nitrile gloves and using Chemwipes to absorb the formamide and then disposing of the wipes in the hazardous waste container.

Figure 1—Pipetting formamide into wells inside a non-ventilated enclosure in the Mitochondrial and Nuclear DNA Unit.

Firearms and Toolmarks Unit

The Firearms and Toolmarks Unit employees examined evidence related to firearms, ammunition, tools, and toolmarks (the physical characteristics left by objects found at a crime scene). They studied bullet and cartridge case characteristics, gunshot residue, and shot patterns; tested firearm functionality; compared tools to toolmarks; examined locks and keys; and restored serial numbers for stolen vehicles, heavy equipment, and firearms. Some employees also reconstructed shooting incidents and performed bullet hole and impact analyses at crime scenes.

Employees wore cloth lab coats, nitrile gloves, and safety glasses with side shields when they mixed or used chemicals. They did this work inside a chemical fume hood. Employees discharged all firearms in a two-lane firing range or a wet bullet tank. They wore ear plugs with a noise reduction rating of 33 decibels (dB) or earmuffs with a noise reduction rating of 20 dB or more. They were not required to wear double hearing protection. Recent NIOSH research on hearing protectors for impulse noise exposures has shown that the combination of ear plugs and muffs, if properly fitted and worn, can attenuate noise levels by 36–49 dB (Murphy et al., 2012; NIOSH, 2013).

In the Firearms and Toolmarks Unit, the HHE team collected 26 surface wipe samples for lead with SKC Full Disclosure wipes. Where possible, a 10 × 10-cm template was used to outline the sample area to obtain a consistent sample size for comparison. For small or irregularly shaped surfaces such as doorknobs, the area of the template was estimated or a sample of the entire area or object was taken.

Lead was found on surfaces in the unit but not in areas where employees ate or drank, such as workstations and the conference room, or where they examined firearms without gloves, such as computer workstations in the ballistics examination area. The HHE team attributed these negative findings to the careful design and proper maintenance of the firing range and ventilation system, which followed NIOSH recommendations (NIOSH, 2009). The firing range had a single entry, a single exit with sticky floor mats, and an air handling system dedicated to the range and wet ballistics tank. Air was supplied to the range through a perforated wall plenum, which distributed the air evenly from floor to ceiling. Airflow tests confirmed that air traveled consistently down the range and exhausted at the bullet trap, with no evidence of turbulence, stagnation, or backflow.

Surfaces on the cart used to transport firearms from the range to the ballistics examination area tested positive for lead, and employees touched this cart with ungloved hands. Except for the cart, all positive samples for lead were from inside the firing range, inside the wet ballistics tank room, and in the air-handling unit for the firing ranges.

The team collected wipe samples on the top of the canopy hood that hung above the area where weapons were test-fired into a wet ballistics tank. These samples were positive for lead. The positive results suggested that lead dust could settle on the canopy exhaust hood and subsequently become airborne. In addition, airflow testing showed that the canopy hood might not sufficiently remove airborne lead from the breathing zone of shooters when the weapons were fired (Figure 2).

Figure 2—Discharging a firearm into a wet ballistics tank inside the Firearms and Toolmarks Unit.

Latent Print Operations Unit

Employees in the Latent Print Operations Unit examined evidence for fingerprints, palm prints, and footprints. Employees dusted with magnetic powders, inspected evidence under visible and ultraviolet light sources, and performed a series of treatments using chemical reactions to lift ridge detail from the latent prints (Figures 3, 4, and 5). After each of the chemical reactions, the employees examined the evidence under the light again. Because employees often placed evidence inside a cyanoacrylate (superglue) fuming chamber, the HHE team was interested in whether employees were being exposed to the chemicals used in the chamber. The PPE used by employees included nitrile gloves, cloth lab coats, and goggles.

Figure 3—Creating a chemical reaction to develop fingerprints, inside the Latent Prints Operations Unit.

Figure 4—Using carbon black to dust for fingerprints, inside the Latent Prints Operations Unit.

Figure 5—Using superglue (ethyl cyanoacrylate) fuming to examine evidence for fingerprints, inside the Latent Prints Operations Unit.

The HHE team used an optical particle counter to evaluate airborne particle exposures at the fingerprint dusting table. The optical particle counter was held near employees while they dusted evidence. The highest particle counts were in the 0.3 to 0.5 micrometer size range, which could indicate potential exposure to fingerprint dusts that are typically 0.3 micrometers in diameter. In addition, when an employee used compressed air to clean the area, it produced a spike in particle counts, indicating that the use of compressed air could increase employee exposure.

The HHE team measured methanol as a surrogate for other chemicals that could not be directly tested. Methanol was not found in any of the 15 personal air samples or 5 area air samples taken outside of the fume hoods. These results indicated that employees had minimal, if any, airborne exposure and that the fume hoods kept methanol from escaping.

No ethyl cyanoacrylate was detected in short-term (55- and 85-minute) personal air samples from employees performing superglue fuming, and no ethyl cyanoacrylate was detected in the 15 area air samples collected around the nine superglue fuming chambers. The area sampling times of 105 to 254 minutes reflect the typical amount of time that employees spend on superglue fuming during a workday.

Operational Projects Unit

Employees in the Operational Projects Unit built crime scene models for court hearings, by means of woodcutting, spray painting, laser cutting of plastics, assembling plastic parts, and 3-dimensional printing. They spray-painted and transferred methylene chloride from 1-quart stock containers into 30-mL containers (for use on the shop floor) in a cross-draft ventilation booth. Plastic parts were assembled with methylene chloride on the shop floor, without the use of local exhaust ventilation. Employees voluntarily wore lab coats, NIOSH-approved Sperian N95 filtering facepiece respirators, ear plugs or earmuffs, and nitrile gloves.

The HHE team used Dräger direct-reading colorimetric detector tubes to evaluate employee exposures to methylene chloride during assembly of plastic parts and during transfer of methylene chloride from large to small containers. No methylene chloride was detected at the limit of detection of 20 ppm.


The evaluation showed the following overall findings about exposure risks: (1) employees would not likely be exposed to airborne formamide above applicable occupational exposure limits, but potential skin exposures could occur if the formamide was spilled; (2) the design of the firing range likely minimized employees’ exposure to airborne lead while firing weapons inside the range, but there was potential for lead exposure from contaminated surfaces in the wet bullet tank room; (3) the fume hoods in the Latent Print Operations Unit appeared effective in preventing airborne exposures to methanol and ethyl cyanoacrylate; and (4) some employees might be exposed to methylene chloride through the skin when using it to combine pieces of plastic and when transferring it from a bulk storage container to a smaller working container.

In investigational laboratories, as in other workplaces, safeguarding employee health and safety is also a means of safeguarding operational efficiency and enhancing the confidence of workers and the public. Requesting this HHE highlighted the FBI’s commitment to establishing best practices in its own operations and in the entire forensics field.

Recommendations and Best Practices for Crime Labs

The recommendations in the HHE report are shown below. We hope other facilities may benefit from these findings and recommendations and will consider how they may apply to their specific operations.

Prioritization: Use a labor-management health and safety committee or working group to discuss potential workplace health hazards and develop an action plan to address them. Prioritize hazards and assess the feasibility of the NIOSH-recommended actions for specific situations. Until hazardous materials or processes can be eliminated and engineering controls are in place, rely on administrative measures and personal protective equipment.

Engineering: Hire a ventilation engineer to improve the effectiveness of the canopy hood ventilation system over the wet bullet trap. Engineering controls such as this protect employees effectively without placing primary responsibility of implementation on the employee.

Work policy: Increase the frequency of cleaning the canopy hood and other surfaces inside the wet bullet tank to reduce lead dust. Post a dated schedule with a checklist that documents when these structures are cleaned. Those cleaning this area should be trained and follow procedures to protect themselves from lead exposure.

Work practice: Provide and require employees to always use (1) gloves for handling methylene chloride and (2) double hearing protection (earmuffs and ear plugs) for impulsive noise generated during weapons firing.

Personal protective equipment: Personal protective equipment should not be the sole method for controlling hazardous exposures, but it should be used until effective engineering and administrative controls are in place. In addition, programs such as training, change-out schedules, and medical assessments may be needed to use PPE correctly.

About the Authors

Seleen S. Collins is a technical writer and editor in the Education and Information Division of NIOSH, in Cincinnati, Ohio. Catherine C. Beaucham is a certified industrial hygienist with the Health Hazard Evaluations and Technical Assistance Branch. Mike Miller is a certified industrial hygienist with the Federal Bureau of Investigations.

Disclaimer: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health (NIOSH). Mention of any company or product does not constitute endorsement by NIOSH.


Murphy, W.J., G.A. Flamme, D.K. Meinke, J. Sondergaard, D.S. Finan, J.E. Lankford, A. Khan, M. Stewart. “Measurement of impulse peak insertion for four hearing protection devices in field conditions”, Int J Aud (2012, 51:S31–S42).

“Preventing Occupational Exposure to Lead and Noise at Indoor Firing Ranges”, NIOSH Alert. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication Number 2009-136 (2009).

Khan A., C.J. Fackler, W.J. Murphy. “Comparison of two acoustic test fixtures for measurement of impulse peak insertion loss,” In-Depth Survey Report. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, EPHB-350-13a (November 2013).

Beaucham C.C., K. Fent, D. Wiegand, M. Seaton. “Evaluation of forensic crime lab employees’ chemical exposures, job stress, and work-related health concerns”, Health Hazard Evaluation Program. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Health Hazard Evaluation Report 2012-0238-3257 (August 2016).

Schlecht P.C., P.F. O’Connor, eds. NIOSH Manual of Analytical Methods (NMAM), 4th ed. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication 94-113 (August 1994); 1st Supplement Publication 96-135; 2nd Supplement Publication 98-119; 3rd Supplement 2003-154,

NIOSH [ND]. Health hazard evaluations (HHEs): HHE program information,

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Item of Interest

The language barrier between English-speaking investigators and Spanish-speaking witnesses is a growing problem. (Updated 28 February 2011)